1. Field of the Invention
The invention relates to a method of integrally casting metal strip close to its final dimensions on a strip-casting apparatus provided with a melt-holding vessel and a conveyor belt. A metal melt, in particular of steel, flows out via a casting nozzle from a closable pouring chamber which can be put under vacuum and is connected via a siphon to a main chamber which can be put under pressure.
2. Description of the Prior Art
During the integral casting of a strip-casting apparatus for producing metal strip close to its final dimensions, air inclusions in the casting nozzle lead to considerable impediments in the casting operation.
EP 0 534 174 discloses methods and the equipment required therefor, which are intended to expel the air from the casting nozzle and the region located upstream. Here, it is first of all proposed to initially set in the melt distributor a filling level which corresponds at most to the conveyor-belt plane and to set during the integral casting such a filling level which expels the melt from a casting nozzle which is curved in a U-shape. It has been found in practice that air collects in the center upper region of the casting nozzle which is curved downward in a U-shape. This essentially leads to the occurrence of an uncontrollable starting surge which can prevent feeding of the strand.
It is therefore also proposed in the EP 0 534 174 to provide a pouring chamber between the melt distributor and the casting nozzle and, during the integral casting--when the inlet of the casting nozzle arranged downstream of a siphon is closed relative to the metal melt--to build up a vacuum in the pouring chamber and to expel the air upward in the casting nozzle.
Even during this procedure, impediments during the integral casting cannot be avoided, since the air bubbles rise in opposite direction to the flow of the metal melt. During the process, uncontrollable constrictions in parts of the casting nozzle occur, which in turn result in an unwanted effect on the spreading of the metal melt on the conveyor belt.